Today, fiberglass air filtration manufacturing methods and formulations can involve the use of oil added after the fiberglass media exits the curing oven to provide for increased entrainment of air contaminants such as dust and particulates. Present solutions handle the problem of capturing increased amounts of dust using the oil method.
The oil additive is undesirable since the oil makes the process more expensive in additive costs, handling costs, and environmental costs and is cosmetically undesirable. Binders are applied to the fibers as they are wound on the drum. Binder mixtures often are comprised of 65% urea formaldehyde and 35% water. In other methods, 1 butyl tackifiers may be mixed into a water emulsion and then mixed with a urea formaldehyde emulsion binder. Urea formaldehyde emulsion is typically used as a binder of glass fibers in the fiberglass filtration industry.
Other patents have mentioned the use of a dry tackifier binder such as polybutene added to a composition to create a tackifier for spraying fiberglass filtration media. For example, see Miller U.S. Pat. No. 6,136,058, entitled “Uniformly Tacky Filter Media,” and Miller U.S. Pat. No. 5,846,603, entitled “Uniformly Tacky Filter Media.” However, the addition of polybutene, while useful, does not reach the MERV 8 rating and higher. In fact, the addition of polybutene barely achieves a MERV 7 rating by itself and then not routinely. Modigliani U.S. Pat. No. 2,546,230, entitled “Glass Product and Method of Making the Same,” and Modigliani U.S. Pat. No. 2,729,582, entitled “Method for Making Unwoven Fabrics,” both mention the use of additives to the fiberglass media. However, in Modigliani U.S. Pat. No. 2,546,230, the binder cited is being utilized for fiber board insulation and is water mixed with urea formaldehyde resin with the addition of an acrylic resin. In Modigliani U.S. Pat. No. 2,729,582, the resin is a vinyltrichlorosilane in a 3.5% solution of xylol, which is not suitable for fiberglass filtration media, but rather more suitable for composites. This disclosure presents a composition that achieves and sustains a MERV 8 rating and higher.
MERV, Minimum Efficiency Reporting Value, commonly known as MERV rating, is a measurement scale designed in 1987 by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) to rate the effectiveness of filters. The scale “represents a quantum leap in the precision and accuracy of air-cleaner” and allows for improved health, reduced cost and energy efficiency in heating, ventilation and air conditioning (HVAC) design as well as increased efficiency. For example, a HEPA filter is often impractical in central HVAC systems due to the large initial pressure drop the dense filter material causes. Experiments indicate that less obstructive, medium-efficiency filters of MERV 7 to 13 are almost as effective as true HEPA filters at removing allergens, with much lower associated system and operating costs. In like fashion, the addition of a polymer compounded with a dry adherent and a resin binder provides for a filter media without a high initial pressure drop.
The scale is designed to represent the worst-case performance of a filter when dealing with particles in the range of 0.3 to 10 micrometers. The MERV rating is from 1 to 16. Higher MERV ratings correspond to a greater percentage of particles captured on each pass, with a MERV 16 filter capturing more than 95% of particles over the full range.
Shown in FIG. 1 is a table grouping MERV ratings by particle size:
Prior techniques exist however for the addition of resins such as acrylate polymers to polyester pleat filtration media and binder (with no urea formaldehyde). However, acrylate polymers have never been combined with urea formaldehyde and polybutene and then applied to fiberglass filtration media.
It would be advantageous to provide a system and method of air filtration formation and media that increase dust holding capacity.
It would also be advantageous to provide a method of formation of MERV 8 or higher air filtration media with fiberglass that does not require the use of oil.
It would further be advantageous to provide a method of controlling the cross-sectional density of the fiber to maximize the dust holding capacity of the filter media while controlling the initial pressure drop.
It would also be advantageous to provide for a finished filter media that feels and looks different from fiberglass.
It would also be advantageous to provide for a fiber that is relatively soft, springy and dry to the touch, with fibers that look more like plastic than fiberglass.
Thus there remains considerable need for binder compositions that provide for less mess and are cosmetically more pleasing to customers while providing for increased dust holding capability at a MERV 8 or better. Additionally, the fiber should be capable of progressive density with a soft springy texture.